Atom probe study of the carbon distribution in a hardened martensitic hot-work tool steel X38CrMoV5-1

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• 作者：Christoph Lerchbacher^a ; ^{christoph.lerchbacher@unileoben.ac.at} ; Silvia Zinner^b ; Harald Leitner^c
• 关键词：Hot-work tool steel ; Martensite ; Carbon distribution ; Retained austenite ; Atom probe tomography
• 刊名：Micron
• 出版年：2012
• 期刊代码：37_09684328
• 类别：ph
• 出版时间：July, 2012
• 卷：43
• 期：7
• 页码：818-826
• 文件大小：2716 K

摘要

The microstructure of the hardened common hot-work tool steel X38CrMoV5-1 has been characterized by atom probe tomography with the focus on the carbon distribution. Samples quenched with technically relevant cooling parameters 位 from 0.1 (30 K/s) to 12 (0.25 K/s) have been investigated. The parameter 位 is an industrially commonly used exponential cooling parameter, representing the cooling time from 800 to 500 掳C in seconds divided with hundred. In all samples pronounced carbon segregation to dislocations and cluster formation could be observed after quenching. Carbon enriched interlath films with peak carbon levels of 6-10 at.%, which have been identified to be retained austenite by TEM, show a thickness increase with increasing 位. Therefore, the fraction of total carbon staying in the austenite grows. This carbon is not available for the tempering induced precipitation of secondary carbides in the bulk. Through all samples no segregation of any substitutional elements takes place. Charpy impact testing and fracture surface analysis of the hardened samples reveal the cooling rate induced microstructural distinctions.